Also killed were three alleged al Qaeda militants and dual New Zealand-Australian citizen Daryl Jones, known as Muslim bin John.

Department of Foreign Affairs documents obtained by the ABC's 7.30 program show Havard and Bin John were individuals of long-standing interest to the Australian Federal Police (AFP) due to their assessed activities in Yemen linked to al Qaeda in the Arabian Peninsula (AQAP).

The AFP was also investigating Havard's possible involvement in the 2012 kidnapping of three Europeans – blamed on al Qaeda.

Havard's mother Bronwyn Dowrick and step-father Neill Dowrick told 7.30 their troubled son had turned his life around after converting to Islam in Townsville in 2008, but he had encountered radical Islam after moving to New Zealand.

"The thing is how did he get down there? Probably through the internet .They (Muslim converts) go through the internet and they can easily be drawn into those sites with radical views and go there," he said.

The ABC in New Zealand has discovered that Havard worked in Invercargill before going to Christchurch.

He was a halal slaughter man at Alliance Group Ltd's meatworks at Lorneville, Invercargill.

The company says he was a full-time employee from mid-December 2011 until early February 2012 when he simply did not turn up for work again.

He had lived in one of the company's share rental houses.

His supervisor at the time said there were no issues with Havard's work and he was a quiet person who kept largely to himself.

New Zealand prime minister John Key would not discuss specific details of the case today, but acknowledged some people are being radicalised and security officials are monitoring them.

"There are people in New Zealand who have certainly converted to a form of Islam and some of those people have gone offshore and got themselves involved in terrorist groups like Al Qaeda. That's a statement of fact," he said.